1. Technical Field
The present disclosure relates to a semiconductor device and a method for manufacturing the semiconductor device.
2. Description of the Related Art
A power semiconductor device is a semiconductor element having a high breakdown voltage and used for passing a large electric current, and is required to be a low-loss element. Conventionally, power semiconductor devices using a silicon (Si) substrate have been widely used, however, power semiconductor devices using a silicon carbide (SiC) substrate are attracting attention and subjected to development in recent years.
Silicon carbide has a higher breakdown voltage than silicon by one digit, and has a characteristic of maintaining a breakdown voltage even with a thin depletion layer at a pn junction or a Schottky contact. Accordingly, use of such silicon carbide enables a reduction in the thickness of a device, and also enables an increase in doping concentration. Thus, silicon carbide is expected as a promising material for power semiconductor devices that achieve low on-resistance, high breakdown voltage, and low loss.
In recent years, vehicles driven by a motor, such as hybrid vehicles, electric vehicles, and fuel cell vehicles, have been developed. Since the above-described characteristics of silicon carbide are advantageous to a switching element of an inverter circuit that drives a motor for these vehicles, silicon carbide based power semiconductor devices for vehicles have been under development.
In a power semiconductor device using a silicon carbide substrate, it is known that a gate threshold voltage may fluctuate in a high-temperature environment. For example, PTL 1 discloses a semiconductor device that suppresses such fluctuation in a gate threshold voltage.